static struct i2c_driver i2cdev_driver;
+/*
+ * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
+ * slave (i2c_client) with which messages will be exchanged. It's coupled
+ * with a character special file which is accessed by user mode drivers.
+ *
+ * The list of i2c_dev structures is parallel to the i2c_adapter lists
+ * maintained by the driver model, and is updated using notifications
+ * delivered to the i2cdev_driver.
+ */
struct i2c_dev {
struct list_head list;
struct i2c_adapter *adap;
}
static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
+/* ------------------------------------------------------------------------- */
+
+/*
+ * After opening an instance of this character special file, a file
+ * descriptor starts out associated only with an i2c_adapter (and bus).
+ *
+ * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
+ * traffic to any devices on the bus used by that adapter. That's because
+ * the i2c_msg vectors embed all the addressing information they need, and
+ * are submitted directly to an i2c_adapter. However, SMBus-only adapters
+ * don't support that interface.
+ *
+ * To use read()/write() system calls on that file descriptor, or to use
+ * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
+ * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl. That configures an anonymous
+ * (never registered) i2c_client so it holds the addressing information
+ * needed by those system calls and by this SMBus interface.
+ */
+
static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
loff_t *offset)
{
return ret;
}
+static int i2cdev_check(struct device *dev, void *addrp)
+{
+ struct i2c_client *client = i2c_verify_client(dev);
+
+ if (!client || client->addr != *(unsigned int *)addrp)
+ return 0;
+
+ return dev->driver ? -EBUSY : 0;
+}
+
+/* This address checking function differs from the one in i2c-core
+ in that it considers an address with a registered device, but no
+ driver bound to it, as NOT busy. */
+static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
+{
+ return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+}
+
static int i2cdev_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
switch ( cmd ) {
case I2C_SLAVE:
case I2C_SLAVE_FORCE:
+ /* NOTE: devices set up to work with "new style" drivers
+ * can't use I2C_SLAVE, even when the device node is not
+ * bound to a driver. Only I2C_SLAVE_FORCE will work.
+ *
+ * Setting the PEC flag here won't affect kernel drivers,
+ * which will be using the i2c_client node registered with
+ * the driver model core. Likewise, when that client has
+ * the PEC flag already set, the i2c-dev driver won't see
+ * (or use) this setting.
+ */
if ((arg > 0x3ff) ||
(((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
return -EINVAL;
- if ((cmd == I2C_SLAVE) && i2c_check_addr(client->adapter,arg))
+ if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
return -EBUSY;
+ /* REVISIT: address could become busy later */
client->addr = arg;
return 0;
case I2C_TENBIT:
res = 0;
for( i=0; i<rdwr_arg.nmsgs; i++ ) {
- /* Limit the size of the message to a sane amount */
- if (rdwr_pa[i].len > 8192) {
+ /* Limit the size of the message to a sane amount;
+ * and don't let length change either. */
+ if ((rdwr_pa[i].len > 8192) ||
+ (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
res = -EINVAL;
break;
}
return -EFAULT;
}
return res;
-
+ case I2C_RETRIES:
+ client->adapter->retries = arg;
+ break;
+ case I2C_TIMEOUT:
+ client->adapter->timeout = arg;
+ break;
default:
- return i2c_control(client,cmd,arg);
+ /* NOTE: returning a fault code here could cause trouble
+ * in buggy userspace code. Some old kernel bugs returned
+ * zero in this case, and userspace code might accidentally
+ * have depended on that bug.
+ */
+ return -ENOTTY;
}
return 0;
}
if (!adap)
return -ENODEV;
+ /* This creates an anonymous i2c_client, which may later be
+ * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
+ *
+ * This client is ** NEVER REGISTERED ** with the driver model
+ * or I2C core code!! It just holds private copies of addressing
+ * information and maybe a PEC flag.
+ */
client = kzalloc(sizeof(*client), GFP_KERNEL);
if (!client) {
i2c_put_adapter(adap);
snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
client->driver = &i2cdev_driver;
- /* registered with adapter, passed as client to user */
client->adapter = adap;
file->private_data = client;
.release = i2cdev_release,
};
+/* ------------------------------------------------------------------------- */
+
+/*
+ * The legacy "i2cdev_driver" is used primarily to get notifications when
+ * I2C adapters are added or removed, so that each one gets an i2c_dev
+ * and is thus made available to userspace driver code.
+ */
+
static struct class *i2c_dev_class;
static int i2cdev_attach_adapter(struct i2c_adapter *adap)
.detach_client = i2cdev_detach_client,
};
+/* ------------------------------------------------------------------------- */
+
+/*
+ * module load/unload record keeping
+ */
+
static int __init i2c_dev_init(void)
{
int res;
projects / linux-2.6-omap-h63xx.git / blobdiff